A programming language is a formal constructed language designed to communicate instructions to a machine, particularly a computer. It can be used to create programs to control the behavior of a machine.
Java,C,
C++,C#

Computer hardware is the collection of physical elements that constitutes a computer system. Computer hardware refers to the physical parts or components of a computer such as the monitor, memory, cpu.

Web development is a broad term for the work involved in developing a web site for the Internet or an intranet. Html,Css,JavaScript,ASP.Net,PHP are one of the most popular technologies.
J2EE,Servlet,
JSP,JSF,
ASP

Mobile application development is the process by which application software is developed for low-power handheld devices, such as personal digital assistants, enterprise digital assistants or mobile phones.
J2ME

A computer network or data network is a telecommunications network that allows computers to exchange data. In computer networks, networked computing devices pass data to each other along data connections.

An operating system is software that manages computer hardware and software resources and provides common services for computer programs. The OS is an essential component of the system software in a computer system.
Linux,Windows